It didn't seem like it, so I went ahead and timed the beginning battle in the ship with the boss on 'normal' and 'fast' battlespeeds.

The actual battle (from the moment the swirling effect that leads into the battle is done to when the boss screams UAGH) took

Seconds with Normal Battle Speed: 40
Seconds with Fast Battle Speed: 37

That's about a 7-8% difference. No point to it really.